 7,725 ton Belmont class technical research ship Built in 1945 as civilian cargo ship Simmons Victory Acquired by U.S. Navy in 1963, commissioned 1964 Mission: To collect, process foreign communications  Attacked on June 8 1967 Escorted to Malta for repairs  Decommissioned in June 1968 Sold for scrap in 1970Source: U.S. Navy

WASHINGTON (CNN) --Tapes released by the National Security Agency shed new light on the 1967 Israeli attack on the USS Liberty that killed 34 Americans and is one of the most controversial mysteries in U.S. Navy history.

The attack, which took placein international waters off the Sinai Peninsula on June 8, 1967, during the Six Day War, also left 171 Americans injured.

The Israelis have always said the attack on the Liberty, which was monitoring communications in the war, was a tragic accident.

But some survivors and senior U.S. officials at the time have said they believe the attack was a deliberate effort to stop American surveillance of Israeli activities during the conflict.

The NSA on Tuesday released audiotapes of Israeli pilots and ground control speaking in Hebrew, along with English transcripts.

The recordings were made by a nearby American surveillance aircraft in the immediate aftermath of the attack.

"For your info, it is apparently an Arab ship," says ground control.

"Roger," says the pilot.

"It is an Egyptian supply ship," says ground control.

"Roger," comes the response.

The NSA released the tapes and transcripts under the Freedom of Information Act in response to a request from Miami Judge Jay Cristol.

An author of a book on the attack, Cristol said the tapes show it was a tragic accident in a time of war -- that the Israelis mistook the ship for an Egyptian one.

"I don't think there's any question that anyone who reads these tapes would be absolutely convinced there was the fog of war out there," Cristol said.

Later on the tape, the Israelis sound confused and concerned. Ground control orders the helicopter pilots to look for survivors and to check their nationality.

"If they speak Arabic -- Egyptians -- you're taking them to Al-Arish. If they speak English -- non-Egyptians -- you're taking them to Lod. Is that clear?" says ground control.

"Roger," says the pilot.

James Bamford, the author of a history of the NSA, believes the tapes suggest the Israelis may have deliberately attacked the U.S. spy ship, perhaps fearing -- for some reason not known -- that it was spying on them.

"Here the transcripts are saying, 'Well, you know, there may be people speaking English on this ship,'" Bamford said. "Why would you say that if it's an Egyptian ship, carrying horses?"

On the tape, after the rescue helicopter pilot tells ground control he sees an American flag on the ship, he receives an order in return.

"They request that you make another pass and check once again whether it is really an American flag," ground control says.

The order suggests the Israelis were surprised at word of a U.S. flag, but it also runs counter to what Israeli fighter pilots and torpedo boat crews have always insisted: That they could not see an American flag.

"Clearly the flag was there," Bamford said, "because the intercepts show that the helicopter pilots saw it immediately, before they ever even got up to the ship."

The ship's flag now hangs in the National Cryptologic Museum in Fort Meade, Maryland, adjacent to NSA headquarters.

"I think this is probably the most important link in the evidence that ought to bring closure to this matter," Cristol said.

Surviving members of the Liberty crew argue that -- far from putting the matter to rest -- the tapes only underline the continuing need for a full, public U.S. investigation.

"A simple investigation -- that's all they have to do," said Joe Meadors, a Liberty survivor. "Find out what happened. If anybody did anything wrong, punish them."

In a letter to Cristol, the NSA said that contrary to rumors there was no U.S. submarine in the area watching, and the Liberty itself made no relevant recordings.

Israeli Embassy spokesman Mark Regev said the tapes are "further evidence that the Liberty incident was a terrible and tragic case of mistaken identity."